The fur of mammals in exposed environments; do crypsis and thermal needs necessarily conflict? The polar bear and marsupial koala compared

  title={The fur of mammals in exposed environments; do crypsis and thermal needs necessarily conflict? The polar bear and marsupial koala compared},
  author={Terence J Dawson and Koa N. Webster and Shane K. Maloney},
  journal={Journal of Comparative Physiology B},
The furs of mammals have varied and complex functions. Other than for thermoregulation, fur is involved in physical protection, sensory input, waterproofing and colouration, the latter being important for crypsis or camouflage. Some of these diverse functions potentially conflict. We have investigated how variation in cryptic colouration and thermal features may interact in the coats of mammals and influence potential heat inflows from solar radiation, much of which is outside the visible… 
Fitness and fur colouration - testing the camouflage and thermoregulation hypotheses in an Arctic mammal.
This field study provides the first evidence for an effect of colour morph on the reproductive performance of Arctic foxes under natural conditions, with a higher breeding propensity of the blue morph compared to the white one, and suggests an advantage of the dark morph not directly related to disruptive selection by crypsis or thermoregulation.
The functional requirements of mammalian hair: a compromise between crypsis and thermoregulation?
The distal colored band appears to be important for camouflage, whereas the length of the dark proximal hair band facilitates heat gain for energy conservation and allows animals to rewarm quickly and economically from torpor.
Function and underlying mechanisms of seasonal colour moulting in mammals and birds: what keeps them changing in a warming world?
It is found that across species, the main function of SCC moults is seasonal camouflage against snow, and photoperiod is the main driver of the moult phenology, and the synthesis suggests that due to limited plasticity in S CC moulting, evolutionary adaptation will be necessary to mediate future camouflage mismatch.
Variation in fur properties may explain differences in heat-related mortality among Australian flying-foxes
The biophysical effects of these fur properties are complex and contingent on the degree of exposure to solar radiation, but they may help to explain the relatively higher mortality of P. alecto and of juveniles and females that is commonly observed during extreme heat events.
Thermoregulatory costs in molting Antarctic Weddell seals: impacts of physiological and environmental conditions
Thermoregulatory costs calculated from estimated basal metabolic rate and measured HF were more than double for molting seals as compared to those in pre-molt, which suggests that perfusion is increased during molt to support follicle development, despite the increased energetic costs associated with higher HF rates.
Orientation to the sun by animals and its interaction with crypsis
It is shown that body orientations that could optimally use countershading to enhance crypsis are very similar to those that allow optimal solar heat inflow and UV protection, and thatCrypsis has been overlooked as a selective pressure on orientation.
Solar Radiation during Rewarming from Torpor in Elephant Shrews: Supplementation or Substitution of Endogenous Heat Production?
The positive relationship between solar radiation availability and rewarming rate, together with the absence of acclimation in maximum non-shivering and total heat production capacities, suggests that under the conditions of this study solar radiation supplemented rather than substituted metabolic thermogenesis as a source of heat during rewarming from heterothermy.
Energetic costs of mange in wolves estimated from infrared thermography.
The energetic costs of mange in wolves using thermal cameras to estimate heat losses associated with compromised insulation during the winter and predicts how these thermal costs may increase in colder climates by comparing predictions in Bozeman, Montana to those from a place with lower ambient temperatures.
Aposematic signaling and seasonal variation in dorsal pelage in a venomous mammal
It is found that the dorsal stripe of N. javanicus changed seasonally, being longer and more contrasting in the wet season, during which time lorises significantly increased their ground use.


Fur versus feathers: the different roles of red kangaroo fur and emu feathers in thermoregulation in the Australian arid zone.
The effect of coat characteristics on the heat load from solar radiation at skin level and the level of penetration of solar radiation into the coat were important determinants of solar heat load.
The significance of fur structure for solar heat gain in the rock squirrel, Spermophilus variegatus.
  • G. Walsberg
  • Physics
    The Journal of experimental biology
  • 1988
Results demonstrate that the ratio of inner to outer coat depths occurring in rock squirrels is very near that theoretically predicted to minimize solar heat gain, indicating that optimization of fur structure may represent an effective means of adjustingSolar heat gain independent of coat insulation and surface coloration.
Thermal and Energetic Problems of Semiaquatic Mammals: A Study of the Australian Water Rat, including Comparisons with the Platypus
The Australian water rat, Hydromys chrysogaster, faces thermoregulatory problems due to the variation in its thermal environment. The influence of temperature on the rodent's heat budget in air and
Contrasting coloration in terrestrial mammals
  • T. Caro
  • Environmental Science
    Philosophical Transactions of the Royal Society B: Biological Sciences
  • 2008
A survey, collate and synthesize contrasting coloration in 5000 species of terrestrial mammals focusing on black and white pelage, finding that sexual dichromatism is limited in this taxon and its basis is unclear.
Metabolism and heat balance in an arboreal marsupial, the koala (Phascolarctos cinereus)
The combination of a high level of fur insulation, slightly depressed body temperature and reduced level of basal metabolic rate were interpreted as an adaptation to an existence of arboreal folivory extending over a wide latitudinal range.
Seasonal Adjustment of Solar Heat Gain in a Desert Mammal by Altering Coat Properties Independently of Surface Coloration
The results suggest the existence of a previously unknown mode of long-term thermoregulation that allows adjustment of solar heat gain without affecting the animal's external appearance.
The colours of extant mammals.
  • T. Caro
  • Environmental Science
    Seminars in cell & developmental biology
  • 2013
Camouflage, communication and thermoregulation: lessons from colour changing organisms
It is argued that colour changing organisms are ideally suited to experimental and comparative studies of evolutionary interactions between the three primary functions of animal colour patterns: camouflage; communication; and thermoregulation.
Adaptive functions of the colours of desert animals